Fix lettuce tests for course outline page [STUD-1961]

This PR updates the lettuce tests for the course outline feature. Currently all scenarios are passing except for `Collapse link appears after creating first section of a course`, which is failing because `add_section` in `cms/djangoapps/contentstore/features/common.py` is not working properly (currently trying to fix this).

Edit: All tests are now passing. The exception being thrown by `add_section` happened when trying to fill in the section name. Since the course outline story does not require the section to be named, the test no longer initiates this behavior.

@andy-armstrong